Socket cap screw with cross holes



Oct 8, 1968 E, ARTER, R, ET AL 3,404,897

0d. 8, 1968 R CARTER, ET AL 3,404,897

SOCKET CAP SCREW WITH CROSS HOLES Original Filed April 29, 1965 2Sheets-Sheet 2 FIG. 3

2 A92 (if FIG. 4

$ .1... J. ATTORNEY States Patent SOCKET CAP SCREW WITH CROSS HOLESEarle RussellCarter, Jr., Bloomfield, and Edmund West, Glastonbury,Conu., assignors to The Allen Manufacturing Company; Hartford, Conn., acorporation of Delaware Original application Apr. 29, 1963, Ser. No.276,545, now Patent No. 3,204,266, .dated Sept. 7, 1965. Divided andthis application July 16, 1965, Ser. No. 472,471

. 2 Claims. (Cl. 27950) This application is a division of a parentapplication Ser. No. 276,545, filed Apr. 29, 1963, now Patent No.3,204,266 granted Sept. 7, 1965. It is directed to a collet chuckassembly designed especially for supporting a cap screw to facilitatethe forming of radial cross holesin the head of the screw.

A feature of the chuck assembly is a collet having jaws which areperforated in a region which grips the socket head of the cap screw,permits accessof drills and punches to form the radial holes in the headof the screw, and v centralizes the drills and punches in a commonplanerfor this purpose.

In the accompanying drawings:

FIG. 1 is a section taken on line 1--1 of FIG. 2; it shows a blanksocket head of a cap screw gripped in the jaws of a collet, and it showseach of the apertures of the collet as accommodating a hole forming toolin the process of forming cross holes in the head of the cap screw;

FIG. 2 is a detail of the collet partly broken away showing the jaws ofthe collet as having been contracted from a normally open condition;

FIG. 3 is ta longitudinal section of the collet chuck assembly,preparatory to reception of the blank socket head of a cap screw forforming the cross holes in the head; and

FIG. 4 is a view similar to FIG. 3 but showing the head of the cap screwgripped. in the jaws of the collet and showing a hole-punch inoperation.

Referring to .the drawings, there is shown a form of cap screw 30 forwhichthe collet chuck assembly is especiallyadapted. The cap screw 30has the usual threaded shank 31 to which is integrally attached acylindrical head 32. The head has a socket 33 having the shape of aregular hexagonal prism and is adapted to receive the usual hex key.(not shown) by means of which the screw may be. drivemThe socket isdivided into six sectors, each having a flat face 35, defining theperiphery of the socket. One or more of the pairs of opposite wallsectors are intended to be provided with aligned cross holes 36 for thereception of the usual locking tie-wire. These holes are formed bysuitable hole forming tools such as a drill 41 followed by a punch 47.

i YA-collet chuck assembly 186 (FIGS. 3 and 4) is provided to supportthe cap screw during the process of forming the cross holes. A principalfeature of the chuck assembly is a steel collet 140.

Referring to FIG. 2, the steel collet 140 is constructed in one pieceand is hollow from end to end. It comprises for the major portion of itslength a cylindrical portion 165, the rear end of which is provided withexternal screw threads 166 by means of which the collet may be supportedin a stationary-position. The annular wall of the collet is relativelythin along the cylindrical portion 165 but is enlarged to form a head167 at the front end of the collet. At its periphery, the head has aforwardly diverg ing frusto-conical surface 168, a converging surface169 and a reduced cylindrical surface 171. Internally, the head has asurface 172 tapering forwardly toward a bore 173 leading to acounterbore 174, the 'bore and counterbore being separated by a shoulder175 in a plane transverse to the collet axis 176. In order to impartresilience 3,404,897 Patented Oct. 8, 1968 to the collet, the latter isprovided with radial kerfs 177 each extending from the front extremityof the collet, through the head 167 and throughout most of the length ofthe cylindrical portion 165. As shown in FIG. 1, there are three kerfscircumferentially spaced apart, which divide the collet into threesectors or jaws 178. Extending outwardly from the counterbore 174 to theperipheral surface 171 are six radial aperatures 142 countersunk attheir ends 143. As seen in FIG. 1 in a clamped condition of the colletabout the head of a cap screw, the axes of all the aperatures arelocated in a common plane perpendicular to the collet axis 176 and areuniformly spaced 60 apart. Each jaw 178 has two apertures, each located30 from the center line of the adjacent kerf 177.

Referring to FIGS. 2 and 3, one of the functions of the collet 140 is tosupport the blank head of the cap screw or workpiece 30 with the rearextremity of the workpiece head seated against the counterbore shoulderand with the cylindrical periphery 141 of the workpiece head snuglyembraced by the cylindrical counterbore 174 in the sectors 178 wherebythe axis of the workpiece 30 is aligned with the axis 176 of the collet.In order to close the collet on the workpiece, the threaded portion 166is held against axial movement while the forwardly diverging peripheralsurface 168 is cammed inwardly by the action of a cam sleeve 181 whichhas a complementary internal taper and which is subjected to a forwardthrust. In the closed position of the collet as shown in FIG. 2, thecounterbore shoulder 175 lies in a plane perpendicular to the colletaxis 176, the radial axes of apertures 142 also lie in a perpendicularplane, and the counterbore sectors 174 are cylindrical. When the camsleeve 181 is removed, however, the sector jaws 178 expand, causing thecounterbore 174 to diverge forwardly and to move the shoulder 175slightly away from a perpendicular plane. At the same time, the axis ofeach aperture 142 is swung away from the original perpendicular plane,represented by the section line 11 of FIG. 2, and is shifted to anoblique position represented by the center line 183. Moreover, theexpansion of the collet jaws 178 shifts the axes of the apertures 142 ina circumferential sense so that they are no longer precisely radial oruniformly spaced. However, the apertures 142 are properly spaced andextend in a common perpendicular plane when the workpiece 30 is grippedtherein.

In use, the collet 140 forms part of a chuck assembly 186 shownschematically in FIGS. 3 and 4. The assembly includes a chuck body 187having at its rear end an annular flange 188 secured by cap screws 189to any suitable fixture such as a vertical Wall 190. The body has alarge counterbore 191 which encircles and centers 21 back head 192provided with a threaded opening 193 engageable with the threaded end166 of the collet 140 to provide a rigid support for the collet. Thefront end of the collet is provided with means for supporting itrelative to the chuck body on an axis perpendicular to the vertical wall190. The supporting and centralizing means, as shown, comprises a sleeve181 slidably fitting the cylindrical portion 165 of the collet and alsoslidably fitting a small bore 195 in the front wall of the chuck body187. The sleeve 181 is connected to a piston head 196 operable in anintermediate bore 197 to effect closing and opening of the collet jaws.A hose line 199 admits live air to the expansible chamber 201 in frontof the piston head 3 a shown) under semi-automatic control alternatelysupply live air to one hose line while exhausting the other therebyeffecting reciprocation of the sleeve 181. In front of its cylindricalbore, the sleeve 181 has a forwardly diverging frusto-conical surface206 engageable with the tapered surface 168 of the collet 140. When liveair is admitted to the front hose line 199 and vented from the rear hoseline 205, as shown in FIG. 3, the reciprocating sleeve 181 is shiftedrearward to disengage the tapered surface 168 on the collet and permitthe front end thereof to expand radially in response to the inherentresilience or springiness of the collet jaws 178.

In the wide open position of the collet, which is the normal unstressedcondition, the counterbore 174 is enlarged to a size which will permitthe head of the workpiece 30 to be inserted freely. On the other hand,when live air is admitted to the rear hose line 205 and vented from thefront hose line 199, the reciprocating sleeve '181 is shifted forward tocause the frusto-conical surface 206 to exert a camming force on thecollet jaws whereby the collet counterbore 174 firmly grips thecylindrical periphery 141 of the workpiece, as in FIG. 4.

When the workpiece or socket head cap screw 30 is first inserted in thecounterbore 174, it is indexed to move the flat faces of the socket to aposition at right angles with the associated collet apertures 142. Inorder to facilitate such indexing motion and also for other purposes,the chuck assembly 186 is provided with a hex key 207 mounted at thecenter of the collet 140 for axial reciprocation. The hex key has acylindrical body 208 slidably fitting the collet core 173. In front ofthe cylindrical body is a hexagonal portion 209. The latter fits the sixwalls of the workpiece socket 33 and, for the major portion of itslength, has the cross sectional shape of a regular hexagon with sharpcorners. Near the front end of the hexagonal portion 209, the cornersare provided with a chamfer 211 (FIG. 4) which facilitates centering ofthe socket .33 on the hex key 207.

Extending rearwardly from the cylindrical body 208, the hex key 207 hasa shank 212 received within a key holder 213 which is connected to a rod214 which extends rearward through the back head 192 and vertical Wall190. At its rear end, rod 214 is connected to a piston 215 mounted in acylinder 216 supported by a bracket 217 attached to the rear face of thevertical wall 190. The cylinder 216 is provided with hose lines 218 and219 for alternately supplying live air to one end of the cylinder whileventing the other thereby to reciprocate the piston 215 and with it thehex key 207. The rearward position of the hex key is controlled by ascrew 221 threaded into the rear wall of the cylinder 216 and providingan adjustable limit stop engageable with the rear extremity of thepiston 215.

Each of the collet apertures 142 registers with a drill 41 and/or with apunch 47, the axes of which are disposed in a common vertical plane 222perpendicular to the collet axis 174 and therefore parallel to the-vertical wall 190. In a commercial embodiment of this invention, thereare six drills movable radially in unison during the early stages ofoperation, and six punches movable radially'in unison during the laterstages of operation, the latter being arranged to be swung (by shiftingmeans not shown) out of the respective paths of the drills during theearly stages. The number of drills and punches in actual use dependsupon the requirements of the purchaser and may be reduced to four or,two of each, if the purchase order calls for two pairs or one pairofcross holes.

Preferably, the small bore.173, .(FIG..,2) in th:CO1l6t 140 has adiameter substantially equal to that of the cylindricalbody 208 of. thehex" key 207 whereby the key, at least in the FIG'. 3 position, issupported co-axially with the collet bore 174 and therefore in properposition to fit the socket 33 of the workpiece 30. In the rearwardposition of the hex key (FIG. 4) the cylindrical portion 208 lies justto the rear of the collet bore 173'andthe front end of the hex key issupported by the socket 33 in the workpiece. Upon subsequent removal ofthe workpiece and forward movement of the hex key 207, the front end ofthe cylindrical portion 208 engages the tapered surface 172 of thecollet which acts to centralize the hex key and guide it for movementinto the small bore 173. 7

Suitable controls (not shown) are provided for operation of the pistons196 and 215.

What is claimed is: I

1. A tubular collet for holding the cylindrical head of a multi-walledsocket-head screw so as to permit tie-wire holes to be drilledtransversely of the head at a specific location, comprising a rearportion adapted for attachment to a chuck body, a group oflongitudinally extending resilient segmental jaws defining axially oftheir combined front end an annular recess adapted to receive thecylindrical head of a socket-head screw, the recess having an annularshoulder at its bottom as a seat for the head of the screw, the jawsadapted upon being pressed radially inward to clamp the head of thescrew fast after it has been seated in the recess, the wall of therecess having radial drill guide holes countersunk at their outer endsadapted for reception of drill means for drilling tie-wire holes at aspecific location transversely of the head of a screw that might beseated and clamped in the recess, there being an indexing means guideopening extending axially of the shoulder communicating the recess withthe interior of the collet, and indexing means adapted for sliding axialmovement through the opening so as to engage in the socket of the headof a screw that might be seated in the recess, but not as yet clamped inthe recess, to locate in a specific position the walls of the socketrelative to the drill guide holes. i I

2. A tubular collet as in claim 1, wherein each jaw segment has two ofsaid guide holesspaced circumferentially degrees apart.

References Cited UNITED STATES PATENTS 3/1894 Feldt 279-51 8/1949 Ramsey2791 X ROBERT C. RIORDQN, Primary Examiner.

1. A TUBULAR COLLET FOR HOLDING THE CYLINDRICAL HEAD OF A MULTI-WALLEDSOCKET-HEAD SCREW SO AS TO PERMIT TIE-WIRE HOLES TO BE DRILLEDTRANSVERSELY OF THE HEAD AT A SPECIFIC LOCATION, COMPRISING A REARPORTION ADAPTED FOR ATACHMENT TO A CHUCK BODY, A GROUP OF LONGITUDINALLYEXTENDING RESILIENT SEGMENTAL JAWS DEFINING AXIALLY OF THEIR COMBINEDFRONT END AND AN ANNULAR RECESS ADAPTED TO RECEIVE THE CYLINDRICAL HEADOF A SOCKET-HEAD SCREW, THE RECESS HAVING AN ANNULAR SHOULDER AT ITSBOTTOM AS A SEAT FOR THE HEAD OF THE SCREW, THE JAWS ADAPTED UPON BEINGPRESSED RADIALLY INWARD TO CLAMP THE HEAD OF THE SCREW FAST AFTER IT HASBEEN SEATED IN THE RECESS, THE WALL OF THE RECESS HAVING RADIAL DRILLGUIDE HOLES COUNTERSUNK AT THEIR OUTER ENDS ADAPTED FOR RECEPTION OFDRILL FOR DRILLING TIE-WIRE HOLES AT A SPECIFIC LOCATION TRANSVERSELY OFTHE HEAD OF A SCREW THAT MIGHT BE SEATED AND CLAMPED IN THE RECESS,THERE BEING AN INDEXING MEANS GUIDE OPENING EXTENDING AXIALLY OF THESHOULDER COMMUNICATING THE RECESS WITH THE INTERIOR OF THE COLLET, ANDINDEXING MEANS ADAPTED FOR SLIDING AXIAL MOVEMENT THROUGH THE OPENING SOAS TO ENGAGE IN THE SOCKET OF THE HEAD OF A SCREW THAT MIGHT BE SEATEDIN THE RECESS, BUT NOT AS YET CLAMPED IN THE RECESS, TO LOCATE IN ASPECIFIC POSITION THE WALLS OF THE SOCKET RELATIVE TO THE DRILL GUIDEHOLES.